THOMAS Sangster, the young star of British hit movie Love Actually, has landed one of the lead roles in Phineas And Ferb, the cartoon tipped to be the next big thing on our screens.

THE creators of the biggest kids show to come out of the US since High School Musical are delighted it's being broadcast . . . because they've spent 16 years trying to get it on TV.

Animated series Phineas And Ferb became an overnight hit in America after its first episode attracted 10 million viewers in 2007.

On Friday, it hit UK screens and brought with it voices from British actors Thomas Sangster, of Love Actually and Nanny McPhee, and Richard O'Brien from Rocky Horror Picture Show and Crystal Maze.

The cartoon is tipped to be the must-see animation of 2008.

But that's no surprise considering its creators Dan Povenmire and Jeff"Swampy" Marsh have worked on hit comedies including The Simpsons, King Of The Hill, Sponge Bob Square Pants and Family Guy.

What is surprising is the length of time it took TV companies to identify the potential of Phineas And Ferb, an animated comedy about two step-brothers who set out to make their summer holidays the best ever by going on weird and wonderful adventures with their pet platypus Perry.

Dan, who has 20 years' experience in the animation industry, said: "We'd get meetings with TV companies and we'd go from one level to the next.

"Up and up and up and then the last person would turn us down because they didn't get it."

Despite several knock backs, the writers never gave up hope of seeing their characters get their own series, but both admitted it had been an "extremely long time coming" before they finally signed a contract.

Dan added: "We weren't walking away in tears but we always thought it could be done.

"I've carried our original drawings and storyboards with me for years. In the end, it was only by doing a demonstration, almost like a lecture, that Disney saw how it would work."

Now audiences round the world can at last enjoy the 26-part series, and they may hear a few familiar voices. Involving British actors was something writer Jeff was keen on.

"I've lived in the UK for seven years and I was keen that we were able to work with British actors as well," he said.

"We knew Thomas Sangster from Love Actually and Nanny McPhee and he was able to express so much. But he did it in a studio in London and never met or saw anybody else working on the show.

"He'd seen one episode where somebody else was the voice that he had to portray and he just got it.

"But we have a dream list for another series now. We'd love Judi Dench, Ashley Jensen, who we know from Extras and now for her work in America, and stars of the Office."

Thomas, 17, who played Liam Nee son's son in 2003 box office hit Love Actually, provides the voice for Ferb and, after solo studio sessions, finally met with his co-stars last week.

He rubbed shoulders with Vincent Martella (Phineas) from Everybody Hates Chris, Ashley Tisdale (the boys' older sister Candace) from High School Musical and Mitchel Musso (Jeremy) from Hannah Montana at the show's London premiere, marketed as Phineas And Ferbruary, on February 1.

Thomas, who is studying for his A-levels in London, said: "It was strange making Phineas and Ferb.

"I did the voice locked in a studio with a sound guy and the directors in America were telling me what to do via a link.

"The first time I heard my brother, sister and parents talk was when I was given one episode with someone else speaking my lines.

"It was just before I did the recording and it was strange.

"But as soon as I saw the script and knew about the animation, it just seemed fun and something I wanted to do.

"I'm in my last year at school studying art and media studies and they seem to be combining very well with acting. I'm studying film, magazines and newspapers and it's all complementary."

After shooting to fame in Love Actually as the cute little boy with a crush on a girl at his school, Thomas went on to star alongside Emma Thompson for a second time in Nanny McPhee.

And just like in Phineas And Ferb, he did not actually meet most of the cast of Love Actually until its premiere. The teen star is also distantly related to the Love Actually star Hugh Grant, but the only time the pair met was at the premiere and party for the film.

Thomas said: "We're something like cousins once or twice removed, but not close family at all.

"The only time I met him was after we'd made the same film because the script didn't have us in the same scenes. It just worked out that way.

"Hugh and I haven't spoken since Love Actually either. I think we're related on my mother's side but there's many family members between us.

"I've been on TV and done other films but Love Actually, I suppose, was the one that put me on the map.

"It was a very commercial film and full of stars. It was a bit of a boost to have that as my first feature.

"Nanny McPhee continued that. They were both great to work on.

"But working on Love Actually was a bit like doing Phineas And Ferb in that I didn't get a chance to meet the cast until it was finished."

Despite both his parents involved in entertainment - his father Mark is appearing in The Lion King at London's Lyceum Theatre and his mother Tasha Bertram is writing scripts and fronting her own band Winnet - Thomas doesn't feel under pressure to hurry along his career, nor make big plans to further his education.

Other names that crop up in roles in the first series of Phineas And Ferb include Malcolm McDowell, Lucy Davis and Tim Curry.

Creators Dan and Jeff also provide the voices for Dr Doofenshmirtz (Povenmire) and Monogram (Marsh).

Unlike most other animated comedies, Phineas And Ferb is full of "victim-free" humour.

Despite featuring the adventures of two step-brothers, the storyline is not about sibling rivalry or bickering, and no one in particular is the brunt of any of the often side-splitting jokes.

This was something Dan had been aiming for.

He said: "We made a decision early on that we didn't want Phineas And Ferb to have any malice.

"It would be an easy place to go, to have brothers and sisters sniping at each other and being sarcastic. We've seen that so many times.

"We wanted to see if we could do a show that still had some edge to it but the main characters were never really mean.

"We didn't want any jerks or idiots in there either, but it's taken over 16 years to make it happen."

In the series, the likeable pair spend each day making the most of every moment to have the best school holiday of their lives.

Their older sister Candace constantly wants to get them into trouble but their mother, a former one-hit wonder pop star, never sees any fault with the boys' vigorous pursuit of pleasure.

One day Phineas and Ferb decide to have a stab at a pop career and they succeed with just a few hours' work.

On another day they're determined to create a new season that combines winter and summer and set about making "swinter".